Method of firing tunnel-kilns and convertible furnace therefor



J. B. OWENSL METHOD OFFIRING TUNNEL KILNS AND CONVERTIBLE FURNACE THEREFOR.

APPLICATION FILED JAN. 23-1917.

Patented Oct. 19,1920.

UNITED STATES JOHN B. OWENS, 0F METUCHEN, NEW JERSEY.

METHOD OF FIRING TUNNEL-KILNS AND CONVERTIBLE FURNACE THEREFOR.

To all to 710m it may concern I Be it known that I, JOHN B. OWENS, a citizen of the United States, residing, at Metuchen, county of Middlesex, and State of New Jersey, have invented certain new and useful Improvements in Methods of Firing Tunnel-Kilns and Convertible Furnaces Therefor, of which the following is a specification.

This invention relates to a method of firing kilns and to convertible furnaces for kilns, driers, metallurgical operations and other purposes, the object being to provide a novel method of firing a tunnel kiln and a furnace adapted for the individual, or conjoint, use of solid, liquid, or gaseous fuel and for change from the use of one fuel to another without interrupting the operation of the kiln, drier, or other installation which is heated by the furnace.

While my invention is particularly designed for use as a furnace for kilns, and especially those of the tunnel type, I wish it understood that its use is not thus restricted as it' may be employed in many situations where a furnace is required.

The varying supply of fuels and differ ences in prices thereof from time to time render it desirable for a furnace such as is used forheating kilns to be adaptable for the employment of which ever may, at the time, be the most economical or available. In those locations where trade or other .conditions create'a shortage in coal supply, with incident high prices, fuel oil may happen to be available at reasonable cost. On the other hand, in certain locations natural gas, producer gas, or coke oven gas may be either the most available, or the cheapest, fuelxto use. a

If a plant is equipped with furnaces designed for using only one form of these fuels, it is necessary to remodel the furnace to adapt it to another fuel and the cost of remodeling, in connection with the possibility of having to change back to the original arrangement as .soon as the original fuel is again available, often makes it more economical to suspend operations than to remodel the furnace to take advantage of the available fuelsupply.

The present furnace is provided with means adapting it to the use of solid, liquid or gaseous fuel without alterations, or, a

Specification of Letters Patent.

by the oil or natural gas burners.

I have found that a fixed length of combustion chamber Patented Oct. 19, 1920.

Application filed January 23, 1917. Serial No. 144,071.

combination of fuels may be employed. In the first instance, no interruption of operatlons is necessary when changing from one fuel to another. In the second instance, it may be found that a combination of oil and producer gas can be more economically employed than either one of these fuels alone, or that a low grade of fuel which can be obtained at a comparatively low cost which does not possess sufiicient heat value for generating the required temperature in the furnace, can be used in connection with a richer fuel which will boost the heat to the required point.

lVhen referring to oil, I have reference to anyliquid fuel. The term producer gas, I intend to comprise that class of gases known as lean gases, as distinguished from natural gas which is a rich gas. The term solid fuel, I intend to comprise solid fuel in any form, whether'lump or powdered, or howover introduced.

In my furnace there is provided one or more grates on which solid fuel may be burned; means for admitting producer gas or the like; and means for the admission of natural gas and for the burning of'oil.

Preferably, separate means are provided for,

utilizing oil and natural gas, but the same opening in the furnace wall may be employed for the accommodation of either an oil burner or a natural gas burner. Checker 'work may be erected in thefurnace when gas is used, such "checker work being adaptedto obtain the best heating effect from that fuel.

The furnace or combustion chamber extends alongside'the tunnel, preferably parallel theretmand is fired in the direction of its length, that is lengthwise of the tunnel method of firingv and arrangement of the combustion chamber not only insures substantially complete combustion of the fuel prior to the heatunits passing to the goods or wares in the 'tunnel, but it also prevents blackening, specking, or otherwise discolormg the goods whichthe delivery of unconsumed heat units to the goods would bring about. 7 I

from practical experience preventslany wastage of heat units, as they are entirely consumed, which might not be the case were the combustion chamber either This I is disclosed in the accompanying drawings.

and hereinafter set forth is to be considered as lllustratlve, rather than restrlctlve, of 'the scope of the invention as modified arrangements for carrying out the principle of the invention may be resorted to.

In the accompanying drawings;

Figure l is a horizontal section showing the furnace applied to a tunnel kiln, certain parts being in dotted lines; and

Fig. 2 is an end elevation.

The furnaces 1 are shown applied to a tunnel kiln, a portion of which appears at 2. As-the construction of the furnaces on the opposite sides of the kiln is the same, a descriptionof only one will be given.

The combustion chamber 8 opens into the kiln 2 and has openings at in its wall which communicate with the fire boxes above the grates 5. Fuel openings 6 afford means for introducing fuel into the fire boxes and on to the grates 5. Doors 7 are provided for the openings 6. Below the grates 5 is an ash pit whose ends are closed by doors 8; \Vhen it is desiredto use solid fuel, the same is introduced through the openings 6 and burned inthe usual manner.

The combustion chamber 3 has an open ing 9 communicating with a branch 10 from a main 11 adapted to be supplied with producer gas. A controlling valve 12 enables the flow of gas to the ports 9 to be regulated.

In the wall of the furnace 1 is an opening 13 in which is an oil burner 14 which may receive its supply from any suitable source and under any desired control. For the utilization of natural gas, the burner or pipe used therefor may be inserted in the'opening 13 in substitution for the burner 14:. I prefer, however, to provide a separate opening 15 in the wall of furnace l and to have the natural gas burner 16 installed therein.

Vhen producer gas is used, advantageous results may be obtained by erectingchecker brick work 17 between the furnace 1 and the tunnel 2.

Producer gas supplied from the branches 10 from the main '11 is intended to include any lean gas such as blast furnace gas, or any gas not supplied'under pressure of, say,'one pound or more. Natural gas, gas made from oil, carbureted gas or other gas which can be supplied under pressure will be passed through the burner or pipe 16 whether the. same be located ina separate openlng 15 or in the opening 13. U The heat value ofnatural gas is approximately 1000 B. T. U. per cubic foot; coke oven gas 30013. T. U. per cubic foot; water gas 300 B. T. U. per cubic foot; carbureted gas 600 B. T. U. per cubic foot; producer gas 110 to 17 5 B. T. U. per cubic foot; blast furnace gas 80 to 110 B. T. U. per cubic foot. The temperature to be maintained in the furnace would govern to some extent the pressure under which the gas would be supplied, so that it might be possible that some of the above gases would be used through the low pressure or producer gas connection 10,'and port 9, while the same gas might be compressed and used for another operation through the natural gas burner or pipe 16. Natural gas or other comparatively rich gases do not have to be supplied under high pressure in order to attain the heat which would require the high pressure on a leaner gas.

In my furnace any one, or more, of the heat producing means may be used. Being equipped with means for heating by solid, liquid, or gaseous fuel, no change of original installation is necessary when any given fuel is to be used and the furnace has the practical advantage, previously explained, of adaptability for use of a combination of fuels, such, for instance, as oil and producer gas or coke breeze and blast furnace gas, together. I

The combustion chambers 3 are located outside the tunnel 2 and their greatest lengths extend parallel to, or lengthwise of, the tunnel. The oil burner 14 and the gas burner 16 are arranged for initiating and progressing combustion in the direction of the length of the combustion chamber, that e is, longitudinally thereof and lengthwise of the tunnel kiln. Combustion is thus effectiyely propagated and developed before the gases and products of combustion enter the interior of the tunnel 2, which has distinct advantages in that an oxidizing fire is obtained and blackening, specking, or otherwise 'discoloring or damaging the goods or wares in the tunnel 2 is minimized. The method of firing longitudinally of the combustion chamber and in the direction of the length of the tunnel minimizes the number of unconsumed heat units delivered to the goods or wares inside the tunnel, which result'cannot be obtained when other methods of firing are resorted to.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. In a kiln, a chamber in which the ware is burned, a combustion chamber, opening into'the burning chamber, and means for diinto the burning chamber, a fire-box for burning solid fuel located outside the combustion chamber and in communication therewith through a wall of said chamber, and means extraneous to the combustion chamber for controllably supplying liquid or gaseous fuel to the combustion chamber,

of the tunnel of the kiln in a combustion chamber exteriorly thereof prior to the admission of the products of combustion into the tunnel from said combustion chamber, and admitting the products of combustion derived therefrom into the tunnel.

5. The method of firing a tunnel kiln, consisting in initiating and progressing combustion in the general direction of the length of the tunnel of the kiln in a combustion chamber which extends lengthwise of the tunnel prior to the admission of the products of combustion into the tunnel from said combustion chamber, and admitting the products of combustion derived therefrom into the tunnel. a

6. A tunnel kiln having a combustion chamber extending alongside the tunnel thereof, and means for firing said combustion chamber in a plane substantially parallel to that of thetunnel and thereby producing a maximum number of consumed heat units in said combustion chamber before delivery of the heat and products of combustion to the tunnel.

7. A tunnel kiln having a convertible combustion chamber arranged lengthwise of the tunnel and communicating therewith for the delivery of the heat and products of combustion from said chamber into thetunnel, means for directing into said combustion chamber the heat and products of combustion from any one of a plurality of independent sources of fuel differing in kind and extraneous to said combustion chamber, one of said independent sources of fuel being directed into the combustion chamber in a direction substantially that of the length of the tunnel whereby maximum combustion from said given fuel source may be developed within the combustion chamber prior to admission of the heat and products of combustion therefrom into the tunnel.

In testimony whereof, I hereunto affix my signature.

JOHN B. OWENS. 

